It is well known to those skilled in the art that the most accurate way to install tension into fasteners in a joint is to control tightening by developing an indication of the tension in the fastener either directly from the fastener or another component used with the fastener. Fastener installation based on torque control can result in wide variations in the tension in the fastener because of variations in fastener lubricity, burrs on the thread of threaded fasteners, and variations in the friction at the surface of the joint component against which the bearing surface of a threaded fastener bears.
U.S. Pat. No. 3,187,621, which is incorporated herein by reference, is directed to a load indicator adapted for use with a threaded fastener and intended to develop an indication of proper tensioning of the fastener. This load indicator has a plurality of protuberances which are struck and partially sheared from an annular body to leave indentations in the annular body. With this load indicator in a joint, the protuberances are pushed back into the indentations in the annular body as the joint is tightened and tightening is stopped when the protuberances have been “collapsed” back into the indentations in the annular body a prescribed amount. This condition, typically, is sensed by a “feeler” gage inserted into a gap in the joint. U.S. Pat. Nos. 5,015,132, 5,370,483, 5,487,632, 5,667,346, each of which is incorporated herein by reference, also are directed to this type of load indicator.